Pleurodesis is frequently employed to manage malignant pleural effusions. Talc induces pleurodesis by directly initiating inflammation in the pleural space. The injury to the pleura results in intense inflammation with secondary collagen deposition. The aim of this study was to compare fibroblast proliferation and collagen deposition by pleural fibroblasts exposed to pleural fluid from patients with successful pleurodesis (SP) versus failed pleurodesis (FP). Pleurodesis was termed “successful” when the effusion did not recur at any time during follow-up to death of the patient, while it was deemed a “failure” if the pleural effusion recurred at any time.
Pleural fluid was collected from 23 patients with malignant pleural effusions and 6 patients with congestive heart failure (control group). The pleural fluid was obtained at the beginning of thoracoscopy (baseline), immediately after thoracoscopy, and at 2, 4, 12, and 24 hours post thoracoscopy. A grading scale (1-9) was used to quantitate the extent of tumor burden. Soluble collagen was estimated using the Sircoll assay. The proliferation of pleural fibroblasts was determined by [3H] thymidine incorporation.
Pleural fluids from patients with SP following intrapleural talc insufflation have a significantly higher capacity to stimulate fibroblast proliferation as compared to pleural fluid from patients with FP (P<0.05). The pleural fibroblasts exposed to pleural fluids from SP patients also demonstrated higher collagen deposition over time when compared to pleural fluids from FP patients. In addition there was an inverse correlation between tumor burden and proliferative activity of the fluids.
We found significantly increased proliferation and increased collagen deposition by pleural fibroblasts when exposed to pleural fluids from patients with SP as compared to pleural fluids of patients with FP. There was an inverse correlation between fibroblast proliferative activity and tumor burden.
The mechanism of action of talc involves the laying down of matrix proteins. Given the negative correlation between success and extent of pleural tumor involvement, earlier diagnosis and treatment of patients may be justified.
M.A. Jantz, None.